Take some water in a pan and transfer the diced banana into it. Add some salt followed by red chilly powder, turmeric powder and some green chillies. Close the pan with a lid and allow it to boil until the banana turns soft.
Meanwhile put the grated coconut, green chillies, garlic, turmeric powder and cumin seeds into a mixie jar. Give a good mix till the ingredients form a paste like consistency.
Add this ground masala into the boiling pan with banana, and mix well. Pour some water and allow it to cook for some time until the water evaporates. When it is done, add curd and combine well. Transfer the curry onto a bowl and keep it aside.
Now for seasoning, heat some oil in a pan and add some mustard seeds, when they pop add some curry leaves and dried red chillies. Season it into the curry and serve hot.